of milwaukee



A. SIMON.

ELECTROMAGNET.

APPLICAUON FILED ocT.1,1911. RENEwED MAY 17, 19m..

1,325,048. l Patented Dee. 16, 1919.

u'NiTED sTATEs PETENT oEEIoE.

ARTHUR SIMON, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER-HAMMER MFG. CO., OF MILWAUKEE, WISCONSIN, A CORPORATION 0F WISCONSIN.

ELECTEOMAGNET.

Specification of Letters Patent.

Application led October 1, 1917, Serial No. 194,142. Renewed May 17, 1919.- Serial'No. 297,905.

To all whom t may concern Be it known that I, ARTHUR SIMON, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of lVisconsin, have invented new and useful Improvements in Electromagnets, of which 'the following is a specification.

This invention relatcsto lockout switches.

'It is particularly applicable to4 lockout switches, although it may be useful in other fields.

Electromagnets are 'designed to remain open when the current in their operating windin or windings is high and to close when tiie current is below a predetermined value. Such switches are particularly adapted for use in starting systemsfor electric motors, since they may be made to remain open to keep a resistance in circuit when ther motor is subjected to an abnormal current, and to close to remove the resistance when the current decreases toa safe value.

Lockout switches usually comprise a closing magnet tending to actuate the switch arm to close the switch, and a holding magnet tending to prevent closing movement of the switch arm. The two magnets -produce varying differences in pull for' different current values so that for current values below a certain point the closing magnet will predominate and close the switch, but for current values above that point the holding magnet will predominate and hold the* 'switch open. As the closing magnet predominates below a certain current valuethere is a possibility of the switch closing at the first rush of current, even though the current eventually is high enough in value to hold the switch open, because the current -in rising to its high value passes through the low values at which the switch will close.

Various means have been devised for pre' venting this undesirable closing of the switch when 'a current that is relativelyhigh 'in value is first supplied to the switch most of which meansinvolve the use ofa damping-coil associated with the magnetic circuit .of the closing magnet to produce a lag. in

the building up 'of the closing'- magnets strength.-

One object of the invention is to provide an improved electromagnet wherein current through a'winding'thereof is controlled to 'delay .the operation of the electromagnet upon the application of suddenly rising excess n current.

.Another object is vto Vprovide improved means for preventing closing of the switch when current at a relatively high value is first supplied to the' switch.

Another object is to provide a lockout- Patentea Dee-16,1919.

Figure -1 is a side elevation of a lockout switch constructed in accordance with the invention.

. Figs. 2 to 6 inclusive are schematic diagrams illustrating diiierent ways of controlling tlie current through lone ofthe windings of the switch.

The electromagnet comprises inl general a switch arm or armature pivoted intermediate its ends. A' closing magnet acts on oneend of the switch arm in a direction to close the switch, and a holding magnet acts on 'the other end of the switch arm in a direction to restrain` the switch from closing. The two magnets exert relatively different pulls for different current values so that the closing magnet predominates over the holding magnet for relatively low current values and closes the switch, and the holding magnet predominates over the closing magnet for relatively high currentvalues and holds the switch open. The switch arm is normally biased to open position. In the switch illustratedthe necessary predomiiiance o f the two magnets is accomplished by providing them with independent magnetic circuits whose relative tey luctance"varies for different current values. The reluctance o the magnetic circuit of the closing magnet increases more rapidly -than the reluctance of the magnetic circuit determined value, the pull exerted by the creasing reluctance,

the holding magnet predominates switch will remain open so which thel switch is set to remain open,

has so declosing magnet rises comparatively little while, because Vof its relatively slowly 1nthe pull exerted by'the holding magnet continues to rise rapidly.

Above the predetermined current value the relative reluctance of the closing magnet has degree that the pull of over the 'magnet and the long as the curthc predeterm ined value. falls below the value lat t e increased to such a pull exerted by theclosing rent remains above lVhen the current reluctance of the closing magnet creased that thepull exerted by the holding magnetis overcome by the pull exerted by the closing magnet and the switch closes. During the relativel short period of time in which the current is rapidly rising from below the predetermined value to above that value the switch -arm is preventedfrom moving by automatically controlling the current in either the winding of the .closing magnet or the winding of the holding magnet, to produce a lagin the pull of the closing dmagnet; or toa'nerease the-pull of Ythe aholdingmagnet. When ,a .lag is` produced -in the pull of the closing magnet the holding magnet, of course, holds the switch open while thefcurrent is passing through the relatively low values at whichthe switch would ordinarily close. T he same effect is obtainedby'incr 'asing relatively the pull of the holding n agnet. If it be desired to control the curr it through the winding of magnet so asto produce a lag in the pu of the closing magnet an electrical device is shunted across the closing `windingso that at the first rush of current the greater proportion of the total current will be shunted varound the closing Winding, but after an interval of time the said electrical device becomes less effective and the greater proportion of the current passes through the closing winding. This produces the necessary lag in the building up of the closing magnets strength.

magnet the electrical device is shunted around the holding winding to the closing l cause, when the circuit of the switch is first" closed, a greater'proportion of the current.

to pass through theholding winding. This has the eect of relatively increasing the pull of the holding magnet so that it will predominatev over .the closing magnet and hold the switch open until the low current values at which the switch is set to close havebeen passed.

In Fig. l, which shows the lockout switch,

the switch arm or armature is shown at 1.

.It carries amovable contact 2, `which cooperates with the stationary7 contact 3. The closing magnet is shown at '4- and the 'hold.

.ing magnet at 5.

so that at the first rush The switch arm 1 is pivoted intermediate its ends to a support G. The switch arm 1 carries a stop der surface of the support 6 and limits the opening movement of the switch arm.

The upper portion of the carries the contact arm 8 with which t contact 2 is associated. The contact'arm 8 is fulcrumed at 9 on the switch arm 1 and is yieldingly urged toward the switch arm by a coilspring suc-h that the contact 2 is adapted to engage the stationary contact 3 before the switch arm seals with the core of the magnet 4. A fter the contacts 2 and 3 come into engagement further movement of the switch arm 1 causes the spring 10 The contact 2 is thereby closed against the pressure of the spring 10 and is given suffi- -cient movement after engagement of the contacts to produce a wiping action.

' The lower portion of the switch arm carries an adjust. ble armature 11 which cooperates with the core of the holding magnet 5. The armature 11 is carried4 by a threaded pin 12 which passes through the switch arm. The-armature 11 may be adjusted by turning the same, as will be obvious from the .in its adjusted position by the lock nut 13. The adjustment of the armature 11 varies the length of the' air gap between the armature and the core of the magnet 5 and therekfore varies the effectiveness of the holding magnet.

An electrical device 14, which may be either a condenser, a ance, a resistance having a positive temperature coefficient, a self inductance, a resistance having a negative coefficient, or any other device capable of producing. the results hereinafter mentioned, is electrically connected with one of the windings of the switch in the manner hereinafter described. This electrical device may, .'f desired, be mounted directly on the panel of the switch as shown in the drawing.

Figs. 2 to 6 inclusive show diagrammatically `some of the different forms that the electrical device 14: may assume andillustrate the manner of connecting this electrical device across the windings of the switch. In all of these figures the upper coil 4 represents the windmg of the closing magnet,

and the lower coil- 5 represents the winding of the holdingmagnet.

In Figs. 2, 3, Vand L1`the electrical device v14 is shunted across the winding of the closing magnet and controls the current in the closing winding-so that at the first rush of current a lag is produced in the building up of the flux of the closing magnet. In Figs. 5 and 6 the electrical device le is vshunted across the winding of the holding'magnet of current the pull to be compressed.,

drawing, and may be locked.

10. The arrangement is non-inductive resist- 7o I switch armll v the winding ever,

65 duce a lag in y the switch open during rising current.

In Fig. 2 the'electrical device 14 is represented 'as being a condenser shunted across 4 of the closing magnet. When the circuit of theswitch is first closed it is obvious that the first rush of current passes through the condenser instead of through the winding 4 of the closing mag- 10 net. This causes a lag in the building up of the closing magnets strength arid permits the holding magnet to become eiiective be- .fore the closing magnet attains its full strength. v

In Fig. 3 the condenser is replaced by a non-inductive resistance. The iii-st rush of current will pass through the non-inductive resistance on account of the inductance of the winding of the closing magnet. Howshortly after the current is first turned on the greater proportion of. th`e current will pass through the. winding 4 of the closing magnet.

In Fig. 4 the electrical device shunted across the winding 4 takes the form gof a resistance having apositive temperature coefficient. The ohmic value of this resist-l ance is normally low and at thefirst rush of current a largepercentage of the current is 80 thereforeshunt/ed around the winding 4.

However, as the resistance in the shunt circuit becomes heated, its ohmic value increases and ,then the vgreater percentageof current passes thouglrthe winding 4'.

Iii Fig; 5 the electrical device 14 takes the form of a self-'nductance which is shunted around the 'winding 5 of the holding magnet. At-the first rush of current the self-inductancecauses the greater percentage of the winding 5 thus relatively increasing the pull of the holding magnet suiiiciently. to cause it to holdV the switch openuntil the relatively low current values at-which the switch would normally close are passed.

In Fig. 6 thesel-inductance of Fig. 5 is predetermined value,

' ture, an

`niagnets strength while the current is rising, -or the current in the holding winding may be controlled to increase the pull of the holding magnet while the current is rising. f In either case the switch will be held open at the lirst rush of current and while the current is passing through its relatively low value to attain its ultimate high value.

Obviously any combination of the devices a'bove described may be used so as to produce both a lag in `the' p ull of the closing magnet and an increase in the pull of the holding magnet. Furthermore, the electrical device 14 may take other forms than those l1erein..disclo'sed, as the forms herein disclosed are merely exemplary.

The invention has been described in connection with a lockout switch having two coils connected in series. It is obvious that these coils might be .connected in. any other way. Furthermore, the invention is applicable to switches of other types, for even if the switch has onl one winding the electrical device for initiaily controlling the passage of current through the winding may be shunted'around this winding to produce a lag in the pull of the winding to prevent closure of the switch while a current relatively high .in value is building up or passing through its low values.

l. A lockout switch comprising an arma# tur -an electromagnet tending to move the sa e, means associated with the switch for holding Ithe armature against movement 'when the current-to the switch is above a and means for automatically controlling theV current in the winding of said -electromagnet for modifying the normal pullof the magnet when current is first supplied'tosaid winding. f

2. -A lockout switch comprising-an varmaelectromagnet tending to movethe same, means' associated with the switch for -holding Ithe armature against movement replaced bya resistance having la negative` temperature coefficient, such for instance as a carbon pile.- As the ohmic 4value ofitlrc |50 carbon pile is normallyrelativelyvhigh at the first rush of current the greater percentage of the current will pass through the` winding 5. As the carbon pile becomes heated its ohmic resistance decreases, thus 55 decreasing the proportion of current which passes through the holding winding'.

l It will nowbe seen that when current is tirst supplied to the switch the current in one orthe other of the two 'windings is con# 5'0 trolled soas toprevent closing of the switch while the current is passing through the relatively low values and is building. up to its full' value. Either the current' in the closing winding may be controlled to prot e bpilding up of the closing predetermined `matically controlling the current in 'the ing the when the Acurrent redetermined value, and meansl connected 1n shunt with thewinding of'said`electromagnet for modifying the normal pull of 'the magnet when current is first supplied to said'winding. .l I

3. A lockout switch comprising anarmature, an electromagnet tending tov move the same, means associ-ated with the switch for' holding lthe armatureY against movement iio to the switch is above a;

when the current to theswitch is above a' value, and means for autowinding of said electromagnet for modifystrength of the magnet when the current isrst supplied to said winding.

4. A lockout switch com vrising an armature, an electromagnet ten in to move the same, means associated with-t e vswitch for holding the armature against movement fik electromagnet, acting upon the armature and i tending to hold the switch open, and an electrical device connected in shunt with the Awinding of one of said electromagnets for corraov'n' infiaters Patent No.' 1,325,048.

controlling the current 'in said winding for the purposel described.

6. An electric swih comprising an armature, an electroinagnet acting upon the armature and tending to close theswitch,` an electromagnct acting upon the armature and tending to hold the switch open, and means for automatically controlling the current in the winding of one of said electromagne's when the current is first supplied to the switch for causing the switch to remain open when a'relatively high current is passing through its low values;

7. An electric switch comprising an armature, an electromagnet acting upon the armature and tending to close the switch, an electromagnet acting upon the armature and tending to hold the switch open, and means comprising an electrical device connected in shunt with the winding of one of saidl.electromagnets to cause the switch to remain open when a relatively high current is passing through its low values.

8. A lockout switch comprising an armature, an electromagnet tendin to Vmove the same, means associated With t e switch for holding the armature against movementv when the/current to the switch is above a predetermined value, an auxiliary circuit associated with the winding of said electromagnet, andmeans whereby the current in 4[SEALJ or 20o-94.

said auxiliary circuit and in said windingis so proportioned when current is first supplied to the winding as to alter the normal pull of the magnet. p

9. An electric switch comprising anal-mature, -an electromagnet acting upon the sana` tending to close the switch, an electron'iagA acting uponsaid armature -tending to hol-.l the switch" open, an auxiliary circuit associated withthe winding of one of said electromagnets, and means .whereby when rurrent is first supplied. to the switch the current is so proportioned in said auxiliary circuit arid said winding as to cause the switch to remain open when a relatively high current is passing through its low values.

10. An electromagnet comprising an armature, a magnet acting on said armature to move the saine, meansassociated with said arma-ture for lioldiiigl the saine against,

rfioveinent when the irrciit through the electromagnet 1s above a predetermined value, and means for automatically con 411. An eleetromagnet comprising a pivoted armature normally biased in one position, a winding acting on said armatureto move the same toanother position, a second winding actingon said armature to retain the saine in its normal position, and meansv 'associated' with one of said windings for..

modifying the relative effects thereof when suddenly 'rising current is applied to the electromagnet.

In witness whereof, I have hereunto subscribed my name in the presence ot two witnesses.

ARTHUR SIMON.

.It is hereby certified that in Letters Patent No. 1,325,048., granted December 16,' 41919, upon 'the ,application of Arthur Simon, of Milwaukee; Wisconsin, for an improvement in-Electromagnetsf an error appears-in. the priiltedspecification 'requiring correction as follows: Page 1, line 8, for .theV words v lockout switches read electromcgnets; and that the said Letters Patent -should'be read with correction therein that' the same may conform to the record ofthe case inthe Patent i M. ii. coU'iJsToN, Acting Uomissner of Pat-ents. 

